Load switch for belt conveyer systems



Oct. 17, 1950 c. o. woon 2,525,847

LOAD SWITCH FOR BELT coNvEYER SYSTEMS Filed April 2, 1949 2627 l M I/I/OZO 27 22 2f :z2 J J5 A fr0/wey Patented Oct. 17, 1950 LOAD SWITCH FOR BELT CONVEYER l i l SYSTEMS Claude G. Wood, Chicago, Ill., assignor to Goodman Manufacturing Company, Chicago, Ill., a corporation of Illinois Application April 2, 1949, Serial No,a 85,078

This invention relates generally to switches contents onto main or gathering conveyors lol cated in the entries. Since the gathering conveyors may be loaded with material received from points inby of the point ci discharge of the lateral conveyor onto the main or gathering conveyor, it is necessary to afford some means of control whereby the lateral conveyor is prevented from discharging its contents onto `the gathering conveyor when the gathering conveyor is loaded in excess of a predetermined amount. Likewise, it is desirable to continue to operate both the lateral and gathering conveyor units when either of the two units is loaded in excess of a predetermined amount or when both are running under no load. Such a belt conveyor system and the control system therefor is shown in applications Serial Nos. 86,079 and 86,080 of Roger M. Buckeridge, for Belt Conveyor Systems, led on April 7, 1949. l

Heretofore, load indicating switches forcon- 8 Claims.` (Cl.` 198-37) trolling circuits in belt conveyor systems have With the foregoing considerations in mind it ffl is an object of the invention to enable the average load condition only of a belt of a belt conveyor system to affect a loadindicating switch in the control circuit for such a system, the load indicating switch being unaffected by minor variations in the load carried by the belt. l

Another object is to provide a load indicating switch for a belt conveyor system whichwill respond to continued loading in excess of a predetermined amount--and which will be unresponsive to minor variations in load in excess oi` a predetermined amount, 1 l c f l I Still another object is to` afford a load sensitive or load indicating switch forca belt conveyor which will overliealoaded belt, theswitch; being provided with a depending load sensing jarm which is movable on: ashaftin anarcuate path, the movement `of theshait being restrainedlby a dashpot for minor" variations in loadedcondi- Vtiener' the belt, and the shaft cooperating with a switch which `is actuated by rotation. of the shaft by the load sensing arm in accordance with the average loaded condition of the belt,

The foregoing and other objects of the inven tion will be apparent from a study of the following description and the drawing which illustrate a preferred embodiment of the invention, and what is now considered to be the best mode of applying the principles thereof, the scope of the invention, however, not being limited by the terms of the description and drawing forming a part of this specification, nor otherwise thanby the terms of the appended Claims.

In the drawing Figure 1 is a partly elevational and partly sec,-` tional view through, a belt conveyor illustrating the load indicator switch according to the present invention; h h

Figure 2 is an end view of the load indicator `switch of Figure 1 looking in the direction of the arrows 2-2 of Figure 1; t t

Figure 3` is a section taken along the line 3er-,3 of Fieurez; and l `Figure 4 is a section taken along the line 4-4 of Figure 2. Referring` now to Figure 1 of the drawings, there is shown a connector frame I in the shape of an inverted pan provided with feet I 5 adapted to rest on a mine floor, for a belt II of a. conveyor belt system. The conveyor belt I I is moved by drive rollers (not shown), and is guided across a horizontal idler roller I2 and between inclined idling guide rollers I3, I3, The guide rollers l2 and I3 are mounted on the connector frame I0,

l the connector `frame i0 having welded thereto an angle I6, the vertical leg of which has welded theretobrackets I'I and IB in which the inclined guide rollers I3 are journaled. The other side of thevertical leg of the angle I6 is provided with brackets I9 which are welded thereto, and which have journaled therein the horizontal guide roller I Thel `connector `frame Il)` also supports an idlingroller 2| for the return or slack side of the belt II; the idling roller 2| `being journlaled at` l eachend asat 22 in the connector frame I0, l

h invention herein except as they are adapted to The connector frame I0 is one of a number` ofmsuch frames spaced throughout the length of the conveyorbelt'll for support thereof, connector `angles 2Q fastened to the `frame Il being provided for maintaining the connector frame ID in connected and spaced relationship, The details of construction of each connector frame and the means for connecting the connector frames I0 in such spaced relationship are no part of the be modiiiedto provide a support `for a load indi,- cating or load sensing switch according `to the present invention.

As shown with `particular reference to Figure 1, the connector frame lll is provided with an inverted U-shaped standard 23, preferably consisting of angle members which are welded together as at 24 and which include end plates 26 overlying the connector frame l0 and having passing therethrough hook bolts 21 which engage the stringer angles 26 fastened on each side of the connector frame l and connecting the frames ill together for support of the belt ll.

Depending from a horizontal leg 28 of the inverted U-shaped standard 23 is a load indicating or load sensing switch indicated generally at 29, which includes a casing 3i which is secured to the horizontal leg of the angle 28 by means of a bracket 32 welded thereto. The casing 3| is provided with a closure 33, which has journaled therein a'shaft 34 which extends exteriorly of the casing 3l Vand protrudes from a hollow boss 36 formed in the closure member 33.

The exterior end of the shaft 34 has fast thereto a depending arm 31 which has secured thereto as by rivets 38 a resilient load sensitive portion or finger 39 which is of such dimensions as to contact fragments F carried by the conveyor belt Il, see Figure 1. The resilient load sensitive finger 39 is so arranged as to be moved with the depending arm 31 in a counterclockwise direction to the dotted line position shown in Figure 2 when the belt l I is loaded to a predetermined height and is transporting fragmentary material F. The resilient finger 39 is of such resiliency that it will permit large fragments Awhich are spaced along the belt il to be transported lwithout causing the depending arm 31 to be moved, as will now be described. The end of the shaft 34 which protrudes into the casing 3l has mounted thereon a gear sector 4l which meshes with a pinion 42, see Figure 4, mounted on a shaft 4 3 which extends into a chamber 44 of a dashpot 46 which is formed as a part of the closure member 33 for the casing 3l. The end of the shaft 43 which extends into the chamber 44 has mounted thereon a hub 41 which supports a movable vane 48 which contacts the cylindrical wall of the chamber 44, and also contacts a substantially circular plate 49 which forms a closure for the chamber 44. The inner cylindrical wall Yof the chamber 44 has extending radially therefrom a xed vane l of such dimension as to provide a small amount of clearance as at 52 between the hub 41 and the fixed vane 5|.

The portion of the shaft 34 which extends into the casing 3l supports a pair of mercury switches 53 and 54, which are held in position between a pair of recessed supporting plates 56 and 51, which are mounted on the shaft 34, and which clamp the mercury switches 53 and 54 into position, the clamping pressure being provided by means of a washer 58 and a nut 59 which is threaded to the end of the shaft 34, the nut 59 also serving to hold the gear sector 4i fast to the shaft`34.

The mercury switches 53 and 54 may be so arranged that the switch 53 is closed when the arm 31 is in the solid line position shown in Figure 2, and sothat the switch 53 will open when theA arm 31 has moved to the dotted line position as shown in Figure 2. Likewise, the switch 54 may be adapted to be opened when the arm 31 is in the solid line position shown in Figure 2 and to be closed when the arm 31 has movedY to the dotted line position shown in Figure 2.

The choice as to whether the switches -53 and 54 shall be opened or closed upon either of the posit1ons of the arm 31 in Figure 2, may be deter- `regular mined by the circuit conditions desired, as disclosed in Buckeridge application Serial No. 86,- 079 for Belt Conveyor Systems, led April '1, 1949.

It will be seen with particular reference to Figure 2 that the free swinging movement of the arm is impeded by the resistance offered to the movable vane 48 in the dashpot 46, since the uid in the dashpot 46 can only move past the restriction 52 afforded between the hub 41 and the fixed vane 5l. It will thus be apparent that the resistance to the movement of the arm 31, afforded by the dashpot 46, will prevent the free swinging movement of the arm 31, at the same time providing for the displacement of the resilient finger 39, which may be displaced at irintervals by large fragments interspersed throughout the length of the conveyor belt Il and transported thereby. It will also be apparent that at such times the height of the load on the belt Il is such that the load carried thereby will tend to rock the shaft 34 in a counterclockwise direction, that such rocking of the shaft 34 can rbe achieved only by a continuous load on the belt ll of such height that the load will be engaged by the resilient finger 39, which will then have been displaced as shown in the dotted line position of Figure "2 by the load beyond a predetermined amount on the conveyor belt Il, since the inherent resiliency of the load sensing finger 39 will rock the arm 31 and the shaft 34 against the impedance of such movement afforded by the dashpot 46.

At such times as the load on the belt l l is such that it will contact the resilient finger only at points near the lower end thereof, the resistance afforded by the dashpot 46 will prevent such rocking movement of the shaft 34, and the switches 53 and 54 mounted on the shaft 34 will not change in condition. Except for such conditions when the resiliency of the load sensing iinger is actually rocking the shaft 34, the weight of the depending arm is sufficient to rock the shaft to the solid line position as seen in Figure 2. i

It will be apparent from the foregoing description that there has been provided a load sensitive or load indicating switch which will respond to different conditions of load of a conveyor belt. When the conveyor belt H is loaded below a predetermined amount the switch will not be operated because of the resistance to such operation afforded by the dashpot 46. When the load condition on the belt Il is in excess of a predetermined amount the resiliency of the load sensing finger 39 will cause the shaft 34 to rock against the resistance afforded by the dashpot 46, thereby operating the switches 53 and 54.

While the invention has Ybeen described in terms of an embodiment which it may assume in practice, the scope of the invention is not intended to be limited in terms of the embodiment shown, nor otherwise than by the scope of the appended claims.

I claim:

1. In a load indicator switch responsive tothe load condition of a belt conveyor transporting fragmented material, a rotatable shaft having an arm depending therefrom adapted to be contacted by material carried by said conveyor belt, said arm comprising a resilient portion adapted to be displaced'by large fragments interspersed throughout the length of'said belt conveyor and a rigid' portion adapted to be displaced upon loading of said belt in excess of a predetermined amount, fluid means Opposing the displacement of said rigid arm portion by the resilient portion in being displaced by large fragments of said material, and switch means adapted to be operated by displacement of said rigid arm portion.

2. In a load indicator switch responsive to the load condition of a belt conveyor transporting fragmented material, a rotatable shaft having an arm depending therefrom adapted to `be contacted by material carried by said conveyor belt, said arm comprising a resilient portion adapted to be displaced by large fragments interspersed throughout the length of said belt conveyor and a rigid portion adapted to be displaced upon loading of said belt in excess of a predetermined amount, fluid means comprising a dashpot having a movable vane connected to said shaft and adapted to be rotated thereby for opposing the displacement of said rigid arm portion by the resilient portion in being displaced by large fragments of said material, and switch means adapted to be operated by displacement of said rigid arm portion.

3. In a load indicator switch responsive to the load condition of a belt conveyor transporting fragmented material, a rotatable shaft having an arm depending therefrom adapted to be contacted by material carried by said conveyor belt, said arm comprising a resilient portion adapted to be displaced by large fragments interspersed throughout the length of said belt conveyor and a rigid portion adapted to be displaced upon loading of said belt in excess of a predetermined amount, fluid means opposing the displacement of said rigid arm portion by the resilient portion in being displaced by large fragments of said material, and switch means carried by said rotatable shaft adapted to be operated by displacement of said rigid armportion.

4. In a load indicator-switch responsive to the load condition of a belt conveyor transporting fragmented material, va rotatable shaft having an arm depending therefrom adapted to be contacted by material carried by said conveyor belt, said arm comprising a resilient portion adapted to be displaced by large fragments interspersed throughout the length of said belt conveyor and a rigid portion adapted tobe displaced upon loading of said belt in excess of a predetermined amount, fluid means comprising a dashpot having a movable vane connected to saidshaft and adapted to be rotated thereby for opposing the displacement Vof said rigid arm portion by the resilient portion in being displaced by large fragments of said material, and switch means carried by said rotatable shaft adapted to be operated by displacement of said rigid arm portion.

5. In combination with a belt conveyor for transporting fragmentary material, a frame adapted to be mounted on said belt conveyor and having a limb overreaching the belt of said conveyor, a load indicator switch responsive to the load condition of said belt conveyor adapted to be secured to 'said overreaching limb, and having a `rotatable shaft including an arm depending therefromadapted to be contacted by material carried by said conveyor belt, said arm comprising a resilient portion adapted to be displaced by large fragments interspersed throughout the length of said belt conveyor and a rigid portion adapted to be displaced upon loading of said belt in excess of a predetermined amount, fluid means opposing the displacement of said rigid arm por- 6 tion by the resilient portion in being displaced by large fragments of said material, and switch means adapted to be operated by displacement of said rigid arm portion.

6. In combination with a belt conveyor for transporting fragmentary material, a frame adapted to be mounted on said belt conveyor and having a limb overreaching the belt of said conveyor, a load indicator switch responsive to the load condition of said belt conveyor adapted to be secured to said overreaching limb and having a rotatable shaft including an arm depending therefrom adapted to be contacted by material carried by said conveyor belt, said arm comprising a resilient portion adapted tobe `,displaced by large fragments interspersed throughout the length of said belt conveyor and a rigid portion adapted to be displaced upon loading of said belt in excess of a predetermined amount, fluid means comprising a dashpot having a movable vane connected to said shaft and adapted to be rotated thereby for opposing the displacement of said rigid arm portion by the resilient portion in being displaced by large fragments of said material, andswitch means adapted to be operated by displacement of said rigid arm portion.

7. In combination with a belt conveyor for transporting fragmentary material, a frame adapted to be mounted on said belt conveyor and having a limb overreaching the belt of said conveyor, a load indicator switch responsive to the load condition of said belt conveyor adapted to be secured to said overreaching limb, and having a rotatable shaft including an arm depending therefrom adapted to be contacted by material carried by said conveyor belt, said arm comprising a resilient portion adapted to be displaced by large fragments interspersed throughout the length of saidbelt conveyor and a rigid `portion adapted to be displaced upon loading of said belt in excess of a predetermined amount, fluid means opposing the displacement of said rigid arm portion by the resilient portion in being displaced by large fragments of said material, and switch means carried by said rotatable shaft adapted to be operated by displacement of said rigid arm portion.

8. In combination with a belt conveyor for transporting fragmentary material, a frame adapted to be mounted on said belt conveyor and having a limb overreaching the belt of said conveyor, a load indicator switch responsive to the load condition of said belt conveyor adapted to be secured vto said overreaching limb, andlhaving a rotatable shaft including an arm depending therefrom adapted to be contacted by material carried by said conveyor belt, said arm comprising a resilient portion adapted to be displaced by vlarge `fragments: interspersed throughout the length of saidfbelt conveyor and a rigid portion adaptedto be displaced upon loading of said belt in excess of a predetermined amount, fluid means comprising a dashpot having a movable vane connected to said shaft and adapted to be rotated thereby for opposing the displacement of said rigid arm portion by the resilient portion in being displaced by large fragments of said material, and switch means carried by said rotatable shaft adapted to be operated by displacement of said rigid arm portion. L CLAUDE O. WOOD.

' No references cited. 

